Recently, phosphorus and organic substances are the origin of water pollution and have caused various diseases in closed area. Therefore it is essential to establish a method for the removal of phosphorus and organic substances in waste water. In this study, we attempted to support microorganism onto gypsum-calcium carbonate composite bodies and discussed the removal properties for phosphorus and organic substances. Microorganisms were supported on the gypsum-scallop shell composite bodies by immersing a culture solutions containing saccharomyceto, bacillus natto and lactobacillus for various time. The effects of particle size of scallop shell powder and immersing time in the culture solution were investigated on the removal properties for phosphorus and organic substances. The removal performance for organic substances of the gypsum bodies increased with increasing the immersing time in the culture solution. However, the phosphorus removal capacity decayed on immersing in the culture solution. The lowering rate of the phosphorus removal capacity increased with increasing the particle size of scallop shell powder and immersing time in the culture solution. When the amount of adhering microorganism increased, the coarse gained scallop shell exposed on the surface of the gypsum bodies, which act as the site for the precipitation of calcium phosphate, was fully covered with microorganisms. Therefore, the phosphorus removal efficiency drastically decreased on immersing in the culture solution for longer durations. On the other hand, because fine scallop shell powder effectively exposed on the surface, the decreasing rate phosphorus removal capacity was relatively small. There is the optimum at particle size of scallop shell powder and the immersing time of culture solutions in producing phosphorus and organic matter removal properties.
The ZnO-Al2O3-SiO2 system is a base system of Bristol glaze which has been used as a traditional glaze. The glass in this system tends to show volume crystallization and is reported to produce transparent glass ceramics in which ZnAl2O4 (gahnite) precipitates. In the crystallization process of ZnO-Al2O3-SiO2 glasses, SiO2 (β-quartz) precipitates occasionally and its precipitation is suppressed by a heat-treatment for nucleation. The precise investigation of the crystallization process showed that ZnAl2Si2O8, precipitates by surface crystallization and a small amount of Zn2SiO4 and Al6Si2O13 by volume crystallization at the first stage of crystallization process. ZnAl2Si2O8 decomposes and Al6Si2O13 reacts with ZnO in the glass to be ZnAl2O4 and SiO2. Since no SiO2 precipitates directly from the glass, the existence of SiO2 means surface crystallization occurred during crystallization.
From a viewpoint of creation of a recycling society, it is essential to establish a method for recycling waste gypsum boards because large amount of gypsum board are scrapped with rehabilitation of architectural structure. For this purpose, we tried to reuse gypsum boards as phosphorus adsorbents and reported that carbonation of gypsum boards was effective method for the preparation of phosphorus adsorbents with high performance. However, the surface layers of carbonated gypsum boards were easy to peel out after immersion in a phosphorus solution due to the dissolution of gypsum. In this study, aiming at improving the durability of the phosphorus adsorbent we attempted to coat the surface of gypsum boards with PVB(Polyvinyl Butyral) before carbonation. Test pieces cut out from commercial gypsum board were coated PVB by immersing in PVB acetone solution and drying in air. The amount of adhering PVB to the gypsum board increased with increasing PVB concentration. The surfaces of the PVB coated gypsum boards were covered with uniform shaped CaCO3 crystals. Although the PVB coated specimens showed slightly low phosphorus removal ratio in the early stage of phosphorus removal, all samples showed high phosphorus removal ratio more than 90% regardless of PVB coating after 5days immersion. Moreover, although the surface of the samples without PVB coating suffered damage on immersing in the phosphorus solutions, the PVB coated samples kept initial appearance even after long-term immersion in the phosphorus solution.
Zinc hydroxide nitrate (ZHN), which has layered structures including NO3- and H2O between the layers, is promising materials for application to an anion exchange. ZHN can be synthesized by direct precipitation adding sodium hydroxide solution to Zn(NO3)2 solution. ZHNs were synthesized at various synthesis conditions to use them as phosphorous removal agents. ZHN precipitates were obtained at pH6, 7 and 9 and aged at 25℃, 60℃, 90℃, 120℃ respectively under hydrothermal conditions. A small part of ZHN precipitates at pH6 and aged at 120℃ transformed to ZnO, however most of ZHN precipitated at pH7 and aged at over 90℃ transformed to ZnO. However, ZHN obtained at pH9 started to transform to ZnO on aging at 60℃ and most of ZHN precipitates transformed to ZnO at over 90℃. For phosphorus removal experiments, single ZHN phase precipitates could remove around 99% phosphate ions in a 100ppm phosphorous solution, and ZHNs containing a large amount of ZnO for the most part showed lower phosphorus removal ratio. Therefore, ZHNs prepared at lower pH and aged at lower temperatures including little ZnO showed high phosphorus removal capability.
For alumina polycrystals doped with MgO and ZrO2 (1000 ~ 10000 ppm), compression and four-point bending tests were carried out. In the early stages of deformation of alumina doped with MgO, diffusional creep controlled by the grain boundary diffusion was dominant deformation mechanism at higher stresses with the stress exponent n ⋍ 1. At lower stresses, on the other hand, deformation with n ⋍ 2 was observed, suggesting that the interface-reaction seemed to control the creep deformation. Strain hardening, resulting from grain growth of Al2O3, was observed during creep tests. Furthermore, Al2O3 doped with higher amounts of dopant deformed at lower stresses, because the strain hardening effect decreased with increasing amount of secondary phase, which suppressed the dynamic grain growth. Although Al2O3 doped with ZrO2 had the same deformation mechanism as MgO dopant, the strain rates of Al2O3 doped with ZrO2 were nearly one-tenth slower than Al2O3 doped with MgO due to the segregation of Zr4+ at the grain boundaries.
Nearly single-phase samples of high-Tc superconductors of the Y-123(YBa2Cu3Oy) phase have been prepared using a domestic microwave oven. Since it is significantly important to control temperature of the sample for microwave heating, the samples were placed into thermally insulated box coated with SiC (susceptor). Weighting of Y2O3, BaO, and CuO with a molar ratio were carried out and mixied with agate mortar for 1 hour. Samples (12 mm in diameter) were pressed with mold at 30 MPa and heated by microwave (2.45 GHz, and 700 W) with the susceptor. The temperature in the susceptor was kept at 850 °C for 10 minutes, and the samples of Y-123 were prepared. The produced sample showed superconductive transition temperature (Tc) by 92 K, and had zero resistance by 85 K. These properties for samples prepared by microwave heating were almost consistent with the samples produced by the conventional solid phase process. Properties of Y-123 sintered by various susceptors were mainly investigated. These results showed that microwave sintering was suitable for rapid heat-treatments of a copper oxide superconductor.
Creep strain equations of Grade 92 steel which is used in boilers and piping systems of ultra-supercritical (USC) thermal power plants were developed based on the results of creep tests using smooth round bar specimens of three different sources of Grade 92 steels. In these equations, primary creep behavior was represented by a power-law function of time and tertiary creep behavior was described by an exponential function of time. Parameters in these equations were determined as a function of creep rupture time which was obtained from each creep rupture curve. The creep strain equations were able to express the creep deformation behavior of each test material with a satisfactory accuracy for a wide range of temperature and stress.
The strain distribution in a multilayered steel composite, which consists of martensite and austenite layers, was evaluated by energy dispersive X-ray diffraction to investigate the homogeneity of deformation in the martensite layer under uniaxial loading. A dog-bone shape specimen with a martensite layer with 0.2 mm in a thickness, sandwiching by austenite layers with 0.4 mm in thickness, was utilized in this study. A change in strains as a function of tensile loading was measured at the center of the martensite layer as well as near the interface between the martensite and austenite layers. Furthermore, the residual strain distributions were measured in the martensite layer of the unloaded specimens after different applied strains. As a result, slight inhomogeneous deformation was found at the beginning of the plastic deformation in the martensite layer although no local deformation was recognized even near the interface between austenite and martensite layers. After further deformation, mismatch of plastic deformation between austenite and martensite layers was reduced, and the martensite layer deformed homogeneously. Therefore, an unstable interface phenomenon might not be caused by the intrinsic factors with a mesoscopic scale discussed in this experiment.
A technique for efficiently selecting a metal film with strong adhesion to a resin with the combination of an orthogonal array and a response-surface method was developed to select appropriate materials for electronics devices. In this technique, at the first step, important factors that significantly influence the adhesion strength were selected from various factors that characterize metal films by use of an orthogonal array with molecular simulations. As a result, the short-side and long-side lattice constants a and b were selected from four metal-film factors (a, b, the electronegativity, E, and the surface energy density, S). At the second step, the adhesion strength was described as a function of the selected important factors by using a response-surface method. From this function, the most appropriate values for a and b that made the adhesion strength maximum were obtained. The values for a and b were obtained as 0.244 nm and 0.423 nm, respectively. At the third step, the most appropriate metal film whose lattice constants were close to a =0.244 nm and b=0.423 nm was selected by use of the data base of lattice constants. As a result, a copper/manganese/nickel-laminated film whose lattice constants were a =0.242 nm and b=0.419 nm was selected as the most appropriate metal film with the strongest adhesion to a resin.